Article of manufacture



July 32 l932 w. R. coLLnNGs ET AL., 1.8679071 ARTICLE 0F MANUFACTURE Find Maren 8. 1929 l y INVENToR ZLfz'/m 7a (b2/ings 91K/ BY DDHCZJ Patented July 12, 1932 UNITED STATES PATENT oFFicE WILLIAM R. COLLINGS AND DONALD L. GIBIB, OF MIDLAND, MICHIGAN, ASSIGNORS 'JTOI THE DOW CHEMICAL COMPANY, OF MIDLAND, MICHIGAN, A. CORPORATION 0F MICHIGAN ARTICLE OF MANU FACTURE Application led March 8', 1929. Serial No. 345,406.

-or moisture proof. Pitch constitutes one excellent waterproofing material for use in this connection, but the inclusion of such pitch in the wall of a bag or like container presents obvious'diiiiculties. The interior of the bag must, of course, have a clean surface and it is equally objectionable for the pitch to be on the outer surface. At the same time the stantially impervious to moisture. Another object is to provide a pliable reinforced waterproof paper that is stronger per unit of reinforcing material than has heretofore been thought possible. advantages will be brought out as the description proceeds.

The term strength used in this connection is.not to be confused with tensile strength which is commonly' used todesignate the transverse and longitudinal strength of a given paper. The term as used by us designates the property of resistance to tearing or rupture exhibited by a given sheet. For example a bag made from a sheet of kraft paper having a longitudinal tensile strength of' 90 pounds per inch, when iilled with 100 pounds of fiaked calcium chloride, will with- Other objects and stand one to three drops of forty inches before rupture. In like manner a ba our improved type of sheet having reinforcing cords spaced at one inch centers and la strength of pounds per inch` width, will normally withstand 25to 35 such drops.

To the accomplishment, of the foregoing and related ends, the invention then consists of the means hereinafter fully described and particularly pointed out in" the claims, the annexed drawing and the following descrip-, tion setting forth but several of the various ways in which the principle of the invention may be utilized. In said annexed drawing Fig. 1 is a view of one form of our present -improved composite sheet; Fig. 2 is a section of Fig. 1 taken alongline A-Ag Fig. 3 is another form of our improved composite sheet;

Fig. 4 is a section of Fig. 3 taken along line Referring rst of all to the form of sheet illustrated in Figs. l and 2, we utilize two layers of stretchable paper 1 and 2, adhesively stuck together with a suitable material 3 such as asphalt having a low susceptibility factor. Imbedded in the adhesive between the paper plies is the reinforcing material consistin of two series of substantially parallel cor crossing each other at approximately right angles and laid diagonally with the edge at an angle of approximately 45. Each of the cords in this case consists of two strands of spun yarn in substantially untwisted close parallel relation to each other. Figs. 3 and 4 illustrate a similar construction wherein each cord consists of three strands of spun yarn 5 in substantially untwisted close parallel relation to each other.

Heretofore reinforced waterproof paper has ordinarily been made with a layer of woven fabric such as cheese cloth interposed between two layers of paper, as shown in U. S. Patent 1,301,605, or a layer of paper with a layer of burlap, Uf S. Patent 798,680.`

made from` 4paper for a number of uses can be produced y diagonally placing the cords with respect to the length of the sheet, these diagonal cords preferably being uniformly spaced and laced in two layers which cross each other 1n superimposed unwoven relation.' While an angle of approximately from the edge of the sheet would ordinarily be preferred for these cords, the invention is not limited Y to this angle since obviously other angles` could be used in equivalent manner. It is further to be understood that the cords may be laid along curved lines and that the two plies of cords may be laid at different angles from the edge. If the cords in this .construction were relatively bulky there would be Ka tendency for bridging and imperfect contact between the components of the sheet at the points where the cords cross each other, such condition being substantially the same as that encountered with a loosely woven coarse threaded fabric. In order to avoid this condition, instead of using single relatively bulky cords, we prefer to use at least two smaller ones, the combined strength of which is equal to the strength of the single cord, these cords being placed side by side in substantially untwisted relation when incorporated in the composite sheet. The multiple cords thus placed are not excessively bulky at the crossing points and thus aid in making a better contact between various components of the sheet.

The waterproof adhesive, if of the asphalt type, should be one that melts at a relatively high temperature and does not become excessively brittle under relatively low temperatures Such a type ofadhesive is said to have a low susceptibility factor. Someforms of asphalt satisfactorily meet this requirement as do a number of pitches, mixtures of asphalt and pitch, and like materails. In like manner some commercial glues have satisfactorily properties making them suitable for this use. The term adhesive, as used herein will accordingly be understood to connote all of the various equivalent waterproof materials having suitable properties for the use described.

The paper used in this composite sheet may begrelatively strong material lin creped or other suitable form. We have found, however, that of these a stretchable or creped paper is in general preferable. Of this type of paper, one having very fine. or close crinkles appears to be the best. When such a paper is`subjected to rough usa e, or a blow, which would ordinarily tear a at sheet between the reinforcing cords, the crinkles in the stretchable paper will partially or fully stretch out at the point receiving the blow and thus normally absorb it without tearing.

Cords to lbe incorporated in the composite sheet may be cotton, jute, hemp, sisal, New Zealand, or anysuch equivalent material. At the present time, of all these, jute is to be preferred as it costs less per unit strength without reaching the condition of excessive bulkiness. The size of cord or yarn to be used to obtain a given strength will, of course, be governed to a certain extent by the comparative price of different size yarns, as well 'as the conditions that the paper is to be subjected to in commercial usage. In other words, two 12 pound strands of yarn may possibly meet the requirements for reinforcing the sheet and still be satisfactory and cheaper than three 8 pound strands used for the same purpose.

Tests with composite sheets of this type show that even though the average reinforcement per. unit area is the same with various spacings, sizes, and number of reinforcing cords, there is considerable dierence in the performance of the ultimate product. Taking two 12 poundsstrands of jute yarn spaced at one inch and incorporated in the composite sheet in manner heretofore described as standard, then six l2 pounds strands of jute yarn spaced at three inches will be equivalent in reinforcing strength per unit area. This spacing of the reinforcing cords, however, it will readily be seen leaves relatively large areas of unsupported paper between the reinforcing cords and is consequentlyl subject to the danger of rupture if roughly handled. Paper having relatively wide spacing such as this, however, would make a satisfactory waterproof building paper. On the other hand if the reinforcing cords are reduced in strength and spaced closer together while maintaining the same unit area reinforcement, it becomes increasingly difficult to obtain proper Contact between the Yvarious components of the sheet, with resultant loss of efficiency and strength. lAt the same time the decrease in strength of the cords makes the more vulnerable to' breakage when subjected to rough usage as indicated by drop tests.

We have found that the preferred yconstruction of such a sheet where it is to be used to make bags for holding relatively heavy materials, such as granular or iaked calcium chloride in standard size packages, is composed of two sheets of vclosely crinkled paper, adhesively fastened together with a layer of asphalt having a low susceptibility factor and having incorporated in such adhesive two layers of double strands of sub. stantially parallel 12 pound jute reinforcing cords crossing each other at approximately right angles and at an angle of approximately 45 from the edges, said cords being spaced from l5 of an inch to an inch apart. While this composite sheet is primarily designed for use 1n making strong waterproof bags, it will be obvious to thoseversed in the art that numerous other uses could be made of it. For instance, it ma be used for Wrapping or covering materia or articles which might be damaged by exposure to the elements. This paper ma also be used satisfactoril as a waterproo building aper.

Other orms may be employed em the features of our invention instead of thldxse explained, change being made in the form or construction, provided the elements stated by any of the following claims or the equivalent of such stated elements be employed.

We therefore particularly point out and distinctly claim as our invention 1. An elastic composite reinforced paper comprising two sheets of creped paper cementitiously united by a layer of adhesive therebetween and having embedded in such adhesive layer a plurality of substantially parallel diagonally laid strands -of spun yarn in two plies crossing each other in unwoven relation.

2. An elastic composite reinforced paper comprising two sheets of creped paper cementitiously united by a layer of adhesive therebetween and having embedded in such adhesive layer a plurality of substantially parallel diagonally laid cords com osed of untwisted strands of spun yarn', said cords being in two plies crossing each other in unwoven relation.

3. An elastic composite reinforced paper comprising two sheets of creped paper cementitiously united by a layer of asphalt 45 therebetween and havin embedded in such asphalt layer a plurahty of substantially parallel diagonally laid cords composed of4 untwisted strands of spuny yarn, said cords being in two plies crossing each other in unwoven relation.

4. An elastic composite reinforced paper comprising two sheets of creped paper cementitiously united. by a layer of asphalt therebetween and having embedded in such asphalt layer a 1plurality of substantially parallel diagona ly laid double strands of spun jute yarn spaced at 0.7 to 1.0 inch apart in two plies crossing each other in unwoven relation.

5. An elastic composite reinforced paper comprising two sheets of orinkled paper cementitiously united by a layer of adhesive of a low susceptibility factor and having embedded in such adhesive layer a plurality of strands of fibrous material laid crosswise in diagonal relation to the edge of the sheet.

6. An elastic composite reinforced paper comprising two sheets of creped paper cementitiously united by a layer of asphalt of low susceptibilit factor and having embedded in such asp valt layer a plurality of i 'strands of'iibrous material laid crosswlse in dia onal relation to the edge of the sheet.

Sgned by us this 27th day of February, 1929. Y

WILLIAM R. coLLINGs. 7 DONALD L. GIBB. 

